Princess Margaret turned away to avoid the attack, with the rest of the British destroyers (most of which had not spotted the German ships and thought that Mentor had struck a mine) following.

While the minefield was laid successfully, the destroyer Matchless, part of the covering force, struck a German mine on the return journey to Harwich.

Minefields would be laid at the exits of the swept channels through the Heligoland Bight, which any German forces sortieing in response would have to pass through, with 10 submarines waiting off the Horns Reef and off Terschelling.

The Battle Cruiser Force would be waiting 35 nautical miles (65 km; 40 mi) off Terschelling, while the battleships of the Grand Fleet would provide distant cover.

[24][25][26] Princess Margaret set off from the Humber on 3 May 1916, escorted by the destroyers Lark and Lucifer, bound for the western end of the Heligoland Bight.

Princess Margaret left her escorts 60 nautical miles (110 km; 69 mi) west of the proposed minefield, continuing alone, and successfully laid 530 mines.

[32] On 28 November 1916 Princess Margaret returned to operations in the Bight when, escorted by the destroyers Ferret, Sandfly and Moorsom, she laid 500 mines 20 nautical miles (37 km; 23 mi) west of Borkum.

[33] Early in 1917, Admiral Beatty, commander of the Grand Fleet, proposed to completely block off the Heligoland Bight with mines.

While this was not practicable at the time owing to a lack of efficient mines, minelaying operations in the Bight continued steadily in January 1917.

[37] On the night of 20/21 April, Princess Margaret, Angora, Wahine and Ariadne laid 1308 mines south west of the Horns Reef, the largest minefield of the war, while on 27/28 April, Princess Margaret, Angora and Wahine laid another 1000 mines 60 nautical miles (110 km; 69 mi) north west of Heligoland.

[39] On 20 May 1917, Princess Margaret, Angora and Wahine laid a field of 1000 mines 7 nautical miles (13 km; 8.1 mi) north of Vlieland.

Princess Margaret continued operations in the Channel until January 1918, when she was withdrawn to take part in the Northern Barrage, a more ambitious plan to block the exits of the North Sea to stop German U-boats from attacking shipping in the Atlantic.

[42] The start of laying the Northern Barrage was delayed by problems setting up bases and by the late arrival of American minelayers,[43] and Princess Margaret, together with Abdiel and the cruisers Aurora, Boadicea and Penelope, laid a series of deep minefields at the entrance of the Kattegat to block passage from the Baltic to the North Sea, and later in February took part in laying a series of minefields near the Dogger Bank.

The ships arrived off Riga from Libau on the evening of 17 December,[51] and found the city in danger of capture by advancing Bolshevik forces.

[52] By Christmas Eve the city was defended by an inadequate force of Baltische Landeswehr, and some Latvian volunteers organised by Marine officers from H.M.S.

[53] As the situation deteriorated, Princess Margaret embarked 392 refugees (mainly British, Allied and neutral civilians) on 28 December, making room for them by discharging arms and ammunition intended for Reval into H.M.S.

[9] On 7 November 1924, Princess Margaret collided with the Danish auxiliary sailing vessel Marie Margaretha in the English Channel 10 nautical miles (19 km; 12 mi) off the Owers Lightship.